Belgian broadcaster RTL reported that his manager, Veerle Van de Poel, said that “there were no complications. He died of old age, his body was simply worn out.”

Van de Poel could not be reached immediately for confirmation.

Thielemans was hospitalized last month after a fall, and reportedly died in his sleep.

Considered the jazz world’s only true harmonica master, Thielemans was also acknowledged for his fine guitar playing and his unusual technique of whistling in sync with his jazz guitar improvisations.

Thielemans’ improvisational style, on harmonica or guitar, was melodically oriented, avoiding technique for its own sake, always in search of a place he often described as somewhere “between a smile and a tear.”

“Sometimes I play a pretty ballad, and I almost cry myself,” he told The Times in 1992. “That’s my nature. Where do you think the blues, or ballads, the good songs, come from? They didn’t come out of a belly laugh … or a military salute.”

Guitarist Pat Metheny, who featured Thielemans on his 1992 album, “Secret Story,” agreed, describing him as “a true poet of melody.”

It was a quality that served him well over the years. In addition to his numerous jazz affiliations, Thielemans can be heard on the film soundtracks to “Midnight Cowboy,” “Sugarland Express,” “French Kiss,” the 1972 version of “The Getaway” and others, as well as commercials for Firestone, Singer, Old Spice and almost any musical environment calling for an atmospheric harmonica.

Unknown to most of the children watching, it is Thielemans’ warm sound that is heard playing the melody in the “Sesame Street” theme song.

His composition “Bluesette,” recorded in Stockholm, has become a jazz classic despite its unusual sound and its waltz rhythm.

“If there’s a piece of music that describes me, it’s that song,” Thielemans told the Associated Press in 1992. “It contains the roots where I was born — the musette, a sort of waltz. There’s not a blue note or syncopation in the melody, yet it’s a blues.”

In addition, the original recording features the 3/4 melody played by Thielemans’ guitar blending in unison with his whistling, an octave higher. The decision to do so, he explained to The Times, was completely spontaneous.

“I went into a studio and started to rehearse it on harmonica, but the producer said, ‘Toots, that’s a pretty song. Why don’t you try to whistle it and play it on guitar?’”

The record became an international hit, and the unique appeal of Thielemans’ guitar and whistling sound became in demand on studio dates reaching from film, television and commercials to pop artists’ recordings.

After lyrics were added by Norman Gimble, “Bluesette” was recorded in more than 100 cover versions – vocal and instrumental.

Jean-Baptiste Thielemans was born in Brussels on April 29, 1922. By the time he was 3, he was playing the accordion, eventually performing at his parents’ cafe. As a teenager, he bought his first chromatic harmonica. The instrument, unlike the more familiar blues harmonica, plays all 12 intervals of the chromatic octave. A self-taught, natural talent, Thielemans was soon imitating the music he heard on the swing music recordings of the 1930s.

Impressed by his playing, his friends began to call him Toots, describing his given name as being “too square.” The new nickname, which Thielemans eventually legalized, was inspired, he said, by Toots Mondello, a saxophonist with the Benny Goodman Orchestra. Later, when he was suffering from pneumonia, a friend brought him a get-well gift of a guitar. Within months he had begun to master that instrument as well, strongly influenced by the playing of the legendary jazz guitarist Django Reinhardt.

By his early 20s, Thielemans was a professional working musician, at the starting edge of a career that included collaborations with artists from virtually every musical genre.

After World War II, he performed with Edith Piaf and Stephane Grappelli in Brussels, and he toured Europe in 1950 with an all-star group led by Goodman. Emigrating to the U.S. in 1951, he arrived in New York City in the heart of the bebop years. A year later, he was playing with the Charlie Parker All-Stars, a band that also included trumpeter Miles Davis.

Thielemans took American citizenship in 1958, settling in New York while maintaining a home in Brussels. For decades, starting in the ‘60s, his harmonica and his blend of guitar and whistling sounds kept him busy in the studios. But he also maintained an active recording career, releasing albums from the late ‘50s well into the new century, including such memorable efforts as “Affinity,” with the Bill Evans Trio, and “The Brasil Project,” a two-CD project featuring such Brazilian stars as Ivan Lins, Caetano Veloso, Milton Nascimento and Gilberto Gil. In more recent years, he recorded and performed frequently with pianist Kenny Werner. His remarkable resume also includes appearances on albums with Paul Simon, Billy Joel, Quincy Jones, Ella Fitzgerald, Jaco Pastorius, Johnny Mathis and others.

“It’s fate that I became a musician,” Thielemans told Down Beat magazine. “I studied math. I was supposed to become an engineer or professor. If it hadn’t been for jazz, I’d still be in Belgium.”

Among his many honors, Thielemans received a National Endowment of the Arts Jazz Masters Fellowship in 2009. He was appointed a baron by King Albert II of Belgium in 2001. And in 2005 he was nominated for the title “The Greatest Belgian,” on the Belgian television show of the same name.

We are heartbroken to announce the loss of our dear friend, jazz legend Bobby Hutcherson, who passed peacefully on Monday, August 15 at age 75, surrounded by his family and loved ones.

The most accomplished vibraphonist and composer to emerge in the latter half of the 20th Century, Bobby redefined the role of the instrument in modern jazz, bringing new levels of technical mastery and harmonic sophistication that had never been heard before. Inspired by Modern Jazz Quartet vibraphonist Milt Jackson, he made his recording debut with pianist Les McCann in 1961 and began an unprecedented 24-year association with the Blue Note Records label on saxophonist Jackie McLean’s 1964 landmark One Step Beyond. From the crucial harmonic structures and pointillistic stabs of color on Eric Dolphy’s avant-garde masterpiece Out To Lunch and his soloistic fire on Joe Henderson’s epochalMode For Joe to the soul jazz grease of Donald Byrd’s Ethiopian Knights, Bobby made indelible contributions to over 250 albums during his Blue Note tenure, and led 23 recordings that introduced the world to the standards “Little B’s Poem,” “Bouquet,” “Components,” “Montara,” and others. Since moving to the Bay Area in the late 1960s, he developed fruitful musical partnerships with both saxophonist Harold Land and pianist McCoy Tyner, and released a string of sessions on the Blue Note, Columbia, Landmark, and Kind of Blue labels. In 2010, the National Endowment for the Arts named Bobby an NEA Jazz Master for his lifetime of contributions to the art form – the highest honor the U.S. bestows on jazz musicians. A great friend and artist with a long history performing on SFJAZZ stages, beginning with a performance at the very first Jazz in the City Festival in 1983, Bobby was a founding member of the SFJAZZ Collective– composing, arranging, and performing with the band from its inception in 2004 through 2007 (video). He was the honoree at the 2010 SFJAZZ Gala, spoke at the groundbreaking event for the SFJAZZ Center in 2012, and performed during the historic Opening Night concert in January, 2013.

The Jazz at Lincoln Center Orchestra, led by Wynton Marsalis, is made up of 15 of the finest soloists, ensemble players, and arrangers in jazz music today. The JLCO travels worldwide performing and reaching out to young listeners to expose those who may not have a strong jazz community or have never heard jazz before. Walter Blanding, Chris Crenshaw, Vincent Gardner, Victor Goines, Carlos Henriquez, Sherman Irby, Ali Jackson, Ryan Kisor, Elliot Mason, Ted Nash, Paul Nedzela, Dan Nimmer, Marcus Printup, Kenny Rampton and Jow Temperley are members of the JLCO.